Prebiotic effect of fructooligo s ac ch aride s on growth and physiological state of rainbow trout,oncorhynchus mykiss (walbaum)

Rainbow trout at an average weight of 240g were examined for the effect of dietary fructo- oligosaccharides in the diet on their growth and physiological state through selected biochemical parameters of the blood plasma. The prebiotic product Profeed® (experimental group,EG) was administered on a continuous basis at a rate of g kg-1 of pellets for 105 days. The best growth performance for the EG was found in 42 days (363 ± 34.7g vs. 340 ± 36.7g,P = 0.003) and in 63 days (387 ± 3 5.6g vs. 364 ± 42.3g,P = 0.011). SGR of the fish from the EG was 0.69% and from the control group (CG) was 0.70%. The feed conversion level was 0.82 in the EG and 0.86 in the CG. Survival rate was 99% (EG) and 98% (CG). The results of the biochemical examination indicate significant differences in the creatinine (28 ± 5.5 vs. 22 ± 3.05 μmol L-1) and the sodium cation (157.9 1.66 vs. 155.7 ± 1.49 μmol L-1) ) level and in the catalytic concentration of alkaline phosphatase (5.18 ± 1.57 vs. 3.43 ± 0.78 μket L-1) ). The positive results of the growth and biochemical tests as well as the favourable feed conversion suggest that it would be worthwhile to test higher concentrations of the Profeed prebiotic product.